To rack your brains is to search your memory hard for something. Rack your brains for the name.
The rack was an instrument of torture, which is exactly the picture intended. It is spelt rack rather than wrack, though both turn up.
1phraserack your brainsTo search your memory hard for something.
“Rack your brains and see whether the street name comes back.”
rack your brains is a phrase.
Practised in Thinking & Memory